Dazzer Posted July 7, 2009 Report Share Posted July 7, 2009 Hi All I've read threads previously about Temp gauge readings, but would be most grateful for an authoritative account... if there is one. Our temp gauge reads 70 mid way and has a zone marked each side of it. Unfortunately the thermostatic control for the electric fan doesn't cut in until 82. So when stationary the temp gauge reads above the 70 zone. I therefore find myself overriding the thermostatic control and manually switching the fan to keep it within the 70 zone. On the move the temp gauge reads 70 dead on. So what is correct, the 70 zone or just above? I've also noticed that Moss sell gauges with an 80 zone? What the **** is going on. Cheers Darren Quote Link to post Share on other sites
67_gt6 Posted July 8, 2009 Report Share Posted July 8, 2009 Is the fan sensor in the top hose? If the fan is coming on at 82 degrees then for a UK car that is about what the temp in the top hose should be.....the standard UK thermostat is 82 degrees I think. If, at that point the fan comes on, the gauge is reading "hot" then it would seem to indicate that the engine is indeed running cool while on the move ? Maybe you are running a hot climate thermostat matched to a similar gauge, assuming that there is such a thing as a hot climate gauge? andy Quote Link to post Share on other sites
Ade-TR4 Posted July 8, 2009 Report Share Posted July 8, 2009 I have a theory: The domed gauges read "185F", when converting to Celsius that gives 86C However..."158F" gives 70C. Anyone else suspect a typo in the Jaeger office (Friday afternoon maybe?) I changed my thermistor for a TR4a type (which suspiciously has a higher resistance...) and voila, the temp gauge now behaves... Where is your temp sensor for the fan? Top or bottom hose? Cheers Adey Quote Link to post Share on other sites
Smokey Posted July 8, 2009 Report Share Posted July 8, 2009 Back in the '60s, we used to change thermostats spring and fall: 165F for the summer and 185F for the winter. With the 165F thermostat, the heater would not provide enough heat. The bottom bar on my temp gauge is at 185F, if I recall correctly. Darren, if your temp gauge is reading correctly, you probably have a 165F thermostat. I'd just let the electric fan work at 82C in traffic - that's certainly not overheating. Quote Link to post Share on other sites
North London Mike Posted July 8, 2009 Report Share Posted July 8, 2009 I have a theory: The domed gauges read "185F", when converting to Celsius that gives 86C Cheers Adey Hi Adey Good point, like you, I also have a domed temp gauge. When hot, she also reads 185, goes up to 200 and the fan kicks in and she goes back to 185 However, 185 is the bottom of the gauge, if it was a modern BL item this would be the 'normal' zone! I have always believed that the gauges are a broadly calibrated guide. I remember setting up a kenlow and they said, run the car to temp, and then keep dialing the kenlow back so that it runs for 60 seconds, this is then the optimum temp for your engine! That was a hot A series which never had a problem. The TR four also runs fine, never overheats despite the gauge topping out at 200, the fan always brings it back down to the bottom of the gauge (i.e.185) Trust your senses and use the gauge as a guide, the 4 pot will tell you when she's hot Meanwhile looking forward to seeing you at the International again, maybe at the forum meeting (12 noon Saturday)? Quote Link to post Share on other sites
Dazzer Posted July 8, 2009 Author Report Share Posted July 8, 2009 Hi Guys Temp control for the fan is located on the steel section of the bottom hose connector, temp sender is stock up top. Never does overheat, although have had it over cooled, forgetting to turn the fan off manual coming down the Swiss passes... just above 30! So I guess as long as the engine sounds OK anywhere between 30 and 100 is fine! I'm glad we sorted that one out. Cheers Darren Quote Link to post Share on other sites
Horse Posted July 21, 2009 Report Share Posted July 21, 2009 I have a 4A fitted with the same gauge as you have with the 70 degree centre marking. When I bought the car it ran hot according to the gauge. As part of my investigation as to why, I removed the thermostat, which I found to be rated at 85 degrees. A quick check in the w/s manual showed that the correct thermostat is rated at 70 degrees - surprise, surprise! Having obtained a 70 degree thermostat at Beaulieu and fitted it, the needle stays bang in the middle of the gauge. I have no thermostatically controlled fan but a fixed fan from, I believe, a TR6. I have yet to have an overheating indication or problem since I fitted the 70 degree thermostat. Horse Quote Link to post Share on other sites
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